setup()

void gbres_comp::setup ( const Matrix * m, int length, int origsyz, int strategy )

private

Definition at line 79 of file res-a2.cpp.

{
  int i;
  originalR = m->get_ring()->cast_to_PolynomialRing();
  if (originalR == nullptr) assert(0);
  GR = originalR->get_gb_ring();
  mi_stash = new stash("res mi nodes", sizeof(Nmi_node));
 
  FreeModule *Fsyz = originalR->make_Schreyer_FreeModule();
  if (length <= 0)
    {
      ERROR("resolution length must be at least 1");
      length = 1;
    }
 
  // If origsyz, and length>1, create Fsyz as a Schreyer free
  // if origsyz is smaller, truncate this module...
 
  if (length > 1 && origsyz > 0)
    {
      if (origsyz > m->n_cols()) origsyz = m->n_cols();
      monomial one = originalR->getMonoid()->make_one();
      const int *mon;
      for (i = 0; i < origsyz; i++)
        {
          if ((*m)[i] == nullptr)
            mon = one;
          else
            {
              Nterm *t = (*m)[i]->coeff;
              mon = t->monom;
            }
          Fsyz->append_schreyer(m->cols()->degree(i), mon, i);
        }
      originalR->getMonoid()->remove(one);
    }
 
  lo_degree = m->cols()->lowest_primary_degree();
  last_completed_degree = lo_degree - 1;
 
  n_nodes = length + 1;
  nodes = newarray(gb_node_ptr, n_nodes);
 
  nodes[0] = new gb_emitter(m);
  nodes[1] =
      new gb2_comp(Fsyz, mi_stash, nodes[0], lo_degree, origsyz, 1, strategy);
  nodes[0]->set_output(nodes[1]);
  if (n_nodes == 2)
    {
      // Don't compute syzygies at all.
      nodes[1]->set_output(nullptr);
    }
  else if (n_nodes >= 3)
    {
      // Compute a resolution to length 'length', with last being
      // a gb node.
      int deg = lo_degree + 1;
      if (origsyz > 0) deg--;
      for (i = 2; i < n_nodes - 1; i++)
        {
          FreeModule *F = originalR->make_Schreyer_FreeModule();
          nodes[i] =
              new gb2_comp(F, mi_stash, nodes[i - 1], deg++, -1, i, strategy);
          nodes[i - 1]->set_output(nodes[i]);
        }
      FreeModule *F = originalR->make_Schreyer_FreeModule();
      nodes[n_nodes - 1] = new gb2_comp(
          F, mi_stash, nodes[n_nodes - 2], deg++, 0, n_nodes - 1, strategy);
      nodes[n_nodes - 1]->set_output(nullptr);
    }
  strategy_flags = strategy;
}

References FreeModule::append_schreyer(), Ring::cast_to_PolynomialRing(), Nterm::coeff, Matrix::cols(), FreeModule::degree(), ERROR, Matrix::get_ring(), GR, last_completed_degree, lo_degree, FreeModule::lowest_primary_degree(), Matrix, mi_stash, Nterm::monom, monomial, Matrix::n_cols(), n_nodes, newarray, nodes, originalR, and strategy_flags.

Referenced by gbres_comp(), and gbres_comp().